Embodiments of the present disclosure generally relate to air delivery systems, such as HVAC, air handling, heat pump, and energy exchange systems, and, more particularly, to air delivery systems having one or more removable and/or adjustable flame-blocking filters.
Currently, Heating, Ventilation, and Air Conditioning (HVAC) systems are certified with respect to Underwriters Laboratories Standard UL1995 in order to prove that they do not pose a significant risk of causing or enhancing a fire. In general, UL1995 certification is required for most, if not all, building codes. In order for a HVAC unit to be UL1995 certified, many of the components in the HVAC unit are required to pass various UL tests. For example, beginning in October 2014, all air-to-air energy recovery devices and filters will be required to pass Standard UL900. The new requirement for the HVAC components to pass UL900 poses a challenge, as certain HVAC components may traditionally be combustible, and UL900 represents a stringent test. During the UL900 test, a component is subjected to a direct flame for 3 min, and smoke generation and flammability is observed.
One approach to pass the UL900 Standard, or other flame tests, is to build a particular component from flame-resistant materials. Such materials may include metals, or materials with flame-resistant properties or additives, such as flame-resistant plastics. In general, flame resistant plastics are more expensive than standard plastics such as, but not limited to, polypropylene, polyethylene, and acrylonitrile butadiene styrene (ABS). However, constructing HVAC components out of special flame-resistant materials is challenging and may be more expensive than using standard materials.